Pulverizing and classifying apparatus



June 7, 1960 J. T. HAlGH ET AL PULVERIZING AND CLASSIF YING APPARATUS Filed Oct. 17, 1956 3 Sheets-Sheet 1 June 7 Filed Oct. 17, 1956 J. T. HAIGH ET AL PULVERIZING AND CLASSIFYING APPARATUS I 3 Sheets-Sheet 2 June 7, 1960 .1. T. HAIGH ETAL 2,

PULVERIZING AND CLASSIFYING APPARATUS Filed Oct. 17, 1956 PM A /7; Tap/Y5)? 3 Sheets-Sheet 3 2,939,638 I I ULv RIZING AND'CLASSIFYING APPARATUS John r. --Haigh and Raymond c. Roloif, 'Minneapolis,

United States Patent Minn assignors -to' Strong-Scott Manufacturin Com-- -pany,rMinneapolis, Minn., a corporation of Minnesota 1Tiled.. 0ct.,17,:19,56,SSeraNo. 616,443

-18 claims, (21. 241-52 inventionrelates; tov apparatus ,for both pulverizing :and ,classifyingmatterin adry state so that a preferred ,particle size is realized int e. discharged product. Qne lobjectsof the present invention .is to :provide apparatus capable Qf pulverizing hard or soft materials in the extreme finenessrange with-a of oversize. More g specifioally, it is envisaged that .,a :unit rconstructed in acc rdance with th ch ng of: the ins an v nt inescapable of-reducinga greatmany-materials to'the lower -;micron;sizes with SSH- 99% of the final; particles beingfinenthanf-five to tenmicrons. Thus,-it-wi1lbeseen that the invention also .hasforian aim-the -,ob ain ,s high product uniformity, there being ;a virtual ---.eli nu' nation.,o -f troublesome oversize ,which is frequently found in sune finefpr u ts- .iAnothertobjeeti of the invention is to provide grinding andclasfsifying apparatus that is :exceedingly versatile.

In ,tliisiregard, it is within the purview of theinvention to indorporate into the apparatus certain adjnstable, features that will permit the re 12 on ofvtheabove-rnentioned fine e se les it aui' v teunri rons-Iaudsv particle size range ofjfifty rnesh orgtl elieabouts J..A"ft r her obje t sl P ev! g ing hara e h fhishlv effi 'as g veral'lfpower consumptionis cbn'cerridi, i mniany instances" appreciably lessTdriving power than demanded by othe'r methods. 1

A still further object of the invention to proyide unitized apparatus 'for performing combined pulverizing and classifying functions that is ,CQmPact and which af: 'fordscomplete accessibility-to all of "the internal partsfin Ratented June :7,- 19,60

.2 thereof having been-broken away .inorder to exposecertain featuresthat would otherwise'be concealed;

Figure 5 is :asectional view taken in the direction of line,5-5 of Figure 2; i a I Figure 6 is a detailed-view, partlyin cross-section,-Qf

therotor assembly for the pulverizer section of-the apparatus; 7 a

Figure 7 is a detail view of the rotor'assembly forthe classifier section; V r

Figure '8 is a fragmentary end view-of Figure 5 taken along.the'lineand-looking inthe direction of the arrows 8- 8 toillustrate the mounting of a-whiz'zerublade on: the secondary classifying plate, said;bla'de beingishownrs man adjusted tilted position in dashed lines; and

Figure 9is an enlarged fragmentary sectional :VieWsOf Figure 8 taken along; the line' and looking in the direction ofv arrows 9-9 to illustrate the mountingwofthe wh zzer blade flange on ,thesecondary-.classifying'plate, and'theten largedaperturefotjmed;in saidplate; V

iFor-the purpose of facilitating the ensuing description the apparatus exemplifying the invention will be o11- sidered as comprising three basic sections including a feeder =10 a;pul :verizer-.,or grinding mill 112anjda classifier 14. Ihefeeder .19 may be of" any conventional construction, but as can be'seen from Figure 4 is of thevariable speed, screwvariety. 5 j Accordingly, thefeeder "10 includes several feed-worms '16 housed a casing '17 and driven bya motor 18 wiaagspeed reduction unit 20. A suitable hopper 22 superimposed above one endLof-the worms r16 permits gravitational introduction of precrushed materialto these worms.

ii e a s j a e inad -lo on sinfjth oarse;

' ,It should perhaps bestatedgat.the outset that the action 'of the pulverizer and classifier sections "12 and 14 are::11o t independent, of eachmther, but as, mentioned above "the description-lends ,itsel-f more readily to describingthem as separatesections. Therefore, referring-110W indetail t the'pulyerizenor grindingimill section l-z, it will be discern'e d that; this section comprises a "cylindrical;casing', 24

including, a fixed closure plate26 at only the inlet-end, ;the

'othenend labeled 27 being, open for communication with the c lassifier section12. The closureplatezfi isiformed with acnute, H in cornrnunication with the discharge ,end

of the feederzsection lfi. Thecasing-Zt isv bolted directly toaabase 30. ;Also mounted .011 thebase 30 is a-pedestal orrstandarda 32 carrying at tits-upper: edge apair ofibearingsf34, 36,for ;journaling ashaft 3 8 of a rotor assembly designated generally-by the: numeral-1,40 and which assemmanufacture andfabricatnthereby further encouraging its-w despread adoption. I

Qther'objects willbe inlpart obvious andiin part pointed ontmorein detailhereinafter I f'f'h invention ,according l' il 'bein e dinth append cla m "Figure 1"Iis a side lelevati nal view .of om ln d p v z ngr n r yin it un fy ng t inven on;

Figure 2 is a plan view. of thefapparatus illustratedin Figure 1,'the view additionally depicting therespective dniving means for the pulverizer and ,class-ifier sections;

' 'Figurefiis an end view of'Figure'Z;

"Figure 4-is a perspective view ofthe apparatus, portions I fleens ts indie feat re 7 const c i n; Qmbintien n ielsemer t .andarrang ment: of pants which will'be exemplifiedflin the c smetics hereafter set forth and the scope of theapplication which i bly isset-forthin adetailed manner in Figure 6. v The rotoressembly Ail-is driven 1b saimotorflzgalso mounted on the base 30 through the intermediary of; abelt 43and,pu1ley.44,,the pulley being attached to i ne endof the s haft,38. Theshaft 38 overhangs the bearing-36 'sufliciently for the support of several annulardiscsor fashiomone being directed -forwardly and the next adjacent one .rearwardlyso that every-other one is on the opposite" side of t heplates. ,This beater orientationmay alsobelnotedfr'om' an ,inspectionofyFigures 5-;and 6-by comparingr the heaters appearing .at thetop with those appearing at .the bottom;v ,Addit-ionally,.;the ;plate 46 sis equippedwithprimary beaters 54a =and-54b-on opposite V sides thereof which-are :located radially inwardlvfromthe beaters 52. The rearprimarybeatersSa are axially cooperable with an:- annular rear grinding ,plate :"56 (:Figur ,)".lof co rugat d enfiguration'for primary s zer eduction of the-materialnenteringsvia the chute 28 whereas the heaters 51 are r adially cooperablewitha ,cylindrical liner 58 which hasbeen'illustrated in Figure 4 as being 3v corrugated. However, in some instances this liner 58 would be perforated or even smooth, the facial configura tion being a factor in the fineness of the grind.

As best observed from Figure 6 the rotor 40 also includes an end plate retainer 60 shrunk onto the shaft 38. This retainer 60 serves to establish a reference position for the plate 46. Inasmuch as it is desired that the discs 46, 4S and 50 be removably stacked on the shaft 38, a pair of spacers 62 are interleaved betweenthe several discs. A retainer cap '64 held captive by a lockwashcr 66 and a nut 68 maintains the stacked relationship of these discs '46, 48 and 50 during operation of the unit.

The casing 24 is provided with a circumferential flange 70 at its open or forward end 27. This flange mates with a flange 72 integrally carried on a casing 74 forming a part of the classifier section 14. Unlike the casing 24,

116a. Consequently, tightening of the bolt 120,

owing to its threaded engagement with the hub 114, will pull said hub to the right as viewed in Figure 7, thereby forcing the collar half 116a against the shaft 94. One or more similar volts 120 will produce the same effect with respect to the lower collar half 116b. The net result is that the primary plate 112 will be firmly retained in whatever axial position into which it is placed beforethis tightening procedure is inaugurated. 'Conversely, the loosening bolt 122, here again a plurality of such bolts in practice, is received in an aperture formed at, the meeting surface of the hub 114 with the collar half 11Gb. Here, though, just the upper half of the aperture is threaded, i.e. the half residing in the collar half 116b,

which is cylindrical, it is to be noted that the casing 74 is frustoconical, as clearly evidenced from Figure 5. The

casing 74 has a fixed end plate 76 forming one wall of a discharge conduit 78. This discharge conduit is con nected to an exhaust blower (not shown). A pair of air gates 80, 82 permit a controlled admission of air into the casing 74, and a removable hand hole cover .84 permits an internal adjustment that will be commented upon later.

The end plate 76 supports an inboard bearing 86 and an outboard bearing 88. The outboard bearing 88'is axially spaced from the inboard one, being supported at the distal end of a U-shaped bracket 90 attached to said end plate 76. A rotor assembly denoted generally by the numeral 92 (see Figures 5 and 7) includes, a shaft 94 journaled for rotation in the bearings 86,- 88 supports a pulley 96 at one end. By way of albelt 98 driven by a motor 100 (Figures 2 and 3) the shaft 94 can be ro- V tated. It should be pointed out, however, that the motor so that the end of the bolt 122 abuts against the bottom of the unthreaded half of the same aperture, i.e. the half in the hub 114. Hence, tightening of the bolt 122, due to its threaded engagement with the collar half 116b,

- will force said hub to the left as viewed in Figure 7, thereby freeing the collar half 116a from its clamped engagement against the shaft 94. As already pointed out, one or more similar loosening bolts 122 would be employed for the collar half 116a. Thus, from the foregoing it 4 is believed apparent that with the classifier section 14 100 is secured to the ;U-shaped bracket 90 by reason of a second bracket 102. V V r Further, it is to be explainedthat the. casing .74 is rendered pivotal withrespect to the casing 24 by means of hinges including an upper and lower hinge arm 104 aflixed to the casing 74 and a second upperand lower hinge arm 106 similarly aflixed to the casing 24. In this way, the classifier section 14 is rendered pivotal metrically opposite the side of-the flange 70 from the 10-. 1

cation of the hinge arms 104 are a ,pair of .swingable hand wheels 108, each havinga shank engageable in a slotted formation or clevis 110 on the flange 72.

Up to this point it has only been mentioned .that the rotor assembly 92 includes a shaft 94. Additionally, the assembly 92 comprises a primary classifying plate 112 which is rotatably carried by that end of the shaft 94 lying adjacent the shaft 38, therebeing a hub 114 on which the plate or disc is mounted. The hub 114 and of course its plate 112 are axially positionable on'the shaft for a purpose soon to be made manifest. Close. inspection of Figure 7 will reveal that the hub 114is actually a sleeve having a tapered bore extending therethrough. This sleeve or hub 114 encircles'a split tapered splined to the shaft 94 by means of a key 118;" In order to simplify the drawing s',ionly one tightening bolt 12!) and only one loosening bolt 122 are pictured since this type of taper lock is of conventional construction. Ac tually a plurality of such bolts would be used. The tightening bolt is received in an aperture formed at the meeting surface of the hub7114 with the collar half 116a. However, only the upper half of the aperture is threaded, i.e. the half in the hub114, so that the end of the bolt 120 abuts against the bottom of the unthreaded half of the same aperture, i.e. the half ,in the collar half swung into the open position pictured in Figure 4 the bolts 120,122 are readily accessible to permit shifting of the primary classifying plate 112 to an optimum axial position along the shaft 94. More will be said herein- 7 after concerning the overall effect of a given axial posi-'.

tion of the plate 112. In the position depicted in Figure 5, however, the plate 112 has been locked to the extreme end of'the shaft 94.

A secondary classifying plate 126 is also part of the :0 tor assembly 92 being carried by the shaft 94 by means of a hub 128 that is also axially positionable along the shaft. The hub 128 differs from'the hub 114 in that it can be clamped directly to the shaft 94 by way of .a radial rextending'set screw 130. Access to this set may be had by removal of the hand hole coyer 84. v ,l

The secondary classifying plate 126 differs markedly from the plate 112 by virtue of-its 'car'ryingfa plurality of peripherally, spaced whizzer blades 132. 'As can-be V observed from Figures 5 and 7, these whizzer blades 132 with respect to the pulverizer section 12. It will of are substantially L-shaped, having a portion .134 angled so as to be parallel to the frusto-conical casing 74. Also each blade 132 is-formed with a mountingfllange 136 having a pair of oversized apertures therein for ,the

. accommodation of anchoring bolts 138. By making the v apertures oversized, sufiicient clearance is provided by which the whizzer blades 132' may be tilted to a pre= ferred angle with respect to a true radial line passing through the center of the plate 126. f

Both of the classifying plates 112 and 126 KI'e PI'Oe vided with a plurality of apertures 140 through which certain of the ground particulate material may pass;

Returning to the pulv erizing section 12 fora moment, 7

since mention has now been made to the primary classi fying plate 112, it is to be observed that the cas ing;24 is equipped with a pair of tailings openings ,142 leading into a pair of tailings conduits144. These conduits 144 extendrearwardly to the inlet chute 28 for. the return of certain material to the inlet end of the pulverizer sec-i tion 12. A slide gate 145 in eachconduit 144' adja-; cent the chute 28 provides a control'medium for gov; erning quickly the quantity of material returned to the inlet and of the. pulverizer' section 12. The primary. classifying plate is adjustable relative to the tailings openings 142 for a reason hereinafter made manifest.

Before describing a typical operation it mightv be-well to review certain basic constructional features that have been built into the combined ,unit comprised ofthesections and 14. Firsbo'f aill it is tobelnotedfthat the rotor --ass'emblies 40 and '92 {are eah -rotatably supported in what mig'ht'be termed a cantilever fashion, inasmuchas the plates*46, l8, 50, 1 12 and' 126 are mounted more to one end of their respective shafts 38, 94- andthe-bearings 34, 36, 86 and 88 for journaling these shafts are satility is introduced .in the stacked make-up of this rotor, for the number of beater plates 46,48 and 50'may be varied to suit different grinding conditions. use 'offewer beater j'p'lates reduces the'effective grinding action, thereby producing'a coar-ser product. In this regard, when a beaterplateis-removed, a standard collar having the same thickness as .the removed plate is substituted in its stead. Quite obviously, .with. the casing 74 disconnected from the casing '24 by disengagement of the hand wheels 108 and their connected shanks from the clevises 110 access may be hadto the nut' 68 and subsequent removal of the desired beater plate (or plates) from its '(or their) stacked .position on the shaft 38.

Considerable leeway is also possible with the rotor as- Here, swinging movement of the casing 74.

The 1 theopening normally closed bytthe cover 84. .Movementalong-the shaft 94 0f this-plate126-towardthe- -rear end-ofthe shaft, i.e. theend-eztrryingthe plate 112,

will increase the radial clearance. prevailing between the whizzerrbla'des 132-,and, the casing .74. Shifting of the secondary classifying j plate I 126;.. iii 'the above direction will have the eifect of: providing less restriction andahence less return to the inlet .endsof the pulverizer section 512 via the tailings.:conduits..144. Consequently,there-' sultantproduc't'will'befcoarser. Also,- the "angle jof the (-1) 'Ihenumber of b'eater plates 46, 48 and 50j'within-the pulverizing section 12.

1(2) Theiposition oftheprim'ary classifying plate 112' within the section 14.

-'(3)"'Ihe'removal ofthe'primary classifying plate. I (4).The.position of,.t he secondary classifying plate (5) Percentage ofipro'du'ct recirculated 'through the internal air classification system as determined by the position ofeithertailings gate 145.

' (6.) The angleof the whizzers 132 onthe secondary classifying'plateil'26.

f(7) "The amount ofair permitted to enter past the 'air gates '80 and"82. v 3 (8) The rate at whichthefeed section 10 is operated.

Thosefact'ors requiring a more major 'changeor replacement of'parts' are as follows;

however, z r ecive' furtherxgrinding beaters1'52 ion'stlrezplatei-50.

' the casing24i by centrifugal forces.

' 12) The zclearance'zbetween the primary heaters 540 and the igrindingplate 56.

' (2) .The clearance between the heaters 52 and the liner 58. '(3l) The type of 'liner 58, ie Whether corrugated, smoother-perforated.

1(4) I'he peripheralspeed of the heaters 52. (5)' Il1e r.p.m. of the primary and secondary classifying plates 1:12 and :126.

-Considering now a typical operation, we will assume that all adjustments have been made for-the'fineness desired and :that the various members are in the relative positions pictured in thedrawings. The'feeder section .10, of course, advances' the pre-crushed material from the hopper 1'22 to ithe inlet; chute 28 through which it falls into thecasing 24 of the pulverizer section 12.

As Jthe pre-crushed anaterial 'enters'the casing 24-it encounters the heaters 54a. Centrifugal forces produced by the :highperipheral speed of-t-he beaters 54a distribute the entering material so that the material is effectively dispersed between the corrugated baok grinding plate 56 Jandsaid heaters 54a. Therefore, a primary reduction .in particle size is realized in this region. .Since thecentrifugal forces act upon the larger and heavier particles :more forcibly than the smaller and lighter aweightzoneslthe great-bulkof the material at this initial-stage moves radially outward, only a-srnall fraction passing through the apertures 51 in the plate 46. After subjection Ito tthe action of =the primary beaters 54a the particlesiare thrown agai-nst :the inside of the casing where it athenzfirstrpasses :between the tips of the heaters 52 on:zthe..plate 46. "Owing :toithe presence of the liner 58 more sizeireductionitakes place. v fient'rifilgalx'forcesawill :keep the most of the larger particles iadjacentzthe liner 58, whereas the fines are carri'edzradiallyainwardzin theair stream and thence through the;'apertures-:51:in-the plate 48. Thoselarger particles remaining zrnext Eto'; the Iliner .558, I of course, -advance be .tweenethe heaters 1:52 on'iithe'pla'te 48 and a re furtherthatzare'z airborne \inwarldly'and :pass through those 1apertures ;51 I located in thetplate'50. The coarser particles, treatment from the .Thernextas'tep the .exposureof the, ground material to the action of the primary classifying-plate 112. "Since both .of rthe {classifying plates 1'12 .and 126 are driven by;the motorr100, .whereas the pulveriz'ing plates 46,48 and 5.0 ware-driven by. ;the vmotor 42 it *follows :that the speed 'Jofzthe Eprimary classifying plate 112 is wholly independent.:'of:the pulverizing plates. At any rate, his to Jae-understood at this' time that r as the pulverized material approaches the primary classifying plate :112 the larger ;partic1es-:are:retained adjacent, the inner side-of The airborne 'fines, Qnitheotherihand, are drawn by the air current-through thesapertures :140Iin the :plate :112. The coarser oft-he larger.particlesgadjacent the. casing 24 will be induced to leaventhe-Icasing via the openings 142 for return to the inlet end of the .pulverizersection 12 forregrinding. Not' only doestheaairialgposition of the plate 112 influence the in this-capacity,;itoo,fthe gates .145 governing the air-ve V locity through :said: conduits.

:F-urther classification .of -.the airborne fines passing through-the openings i140 in the primary classifying plate 11:2:is accomplished :.by=the inclusion of the secondary classifying .plate 126. Here again, centrifugal force plays an importantrole,-'-'for the coarser particles are thrown radial1y 'outward to strike thejfrusto-conical casing-'74. Throughthe actionof the whizzer blades 132 on theplate 126 the larger particles are forced back to ward} the plate-112. These larger particles in the'ir reverse or counter travel "then 'either "exit-through the open aoaaass 7 ings 142, immediately or pass by the peripheral edge of the plate 112 to these openings. In this regard it will be recalled that the primary classifying plate 112 is axiah ly positionable on the shaft 94 and therefore can be posi' tioned toexpose more or less of the openings 142 to either side of said plate 112. Those particles reaching the openings 142 are then returned through the tailings casing and being substantially open at its other end, a

conduits 144 to the inlet end of the pulverizer section 12 for regrinding along with those particles that reach these openings Without passing'through the apertures 140 in the primary classifying plate 112.

The classified particles, that is those not directed rearwardly by the whizzer blades 132, pass through the apertures 140 in the secondary classifying plate 126 into the discharge conduit 78. Air drawn by the external fan (not shown) provides the conveying air to move the pulverized material from the discharge conduit,78 to the dustcollector (also not shown). The degree of lifting action obtainable from the external blower is of course controllable by means of the gates -80, 82. Hence, it is believed readily apparent that the selective action afforded by the exemplified machine will result in the obtaining of a quality control not heretofore realized.

As many widely apparent different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments herein. f

What is claimed:

l. A combined pulverizer and classifier comprising; a pulverizer section including a generally cylindrical casing provided with an inlet at one end for the introduction of material into the casing and being substantially open at its other end, and a rotor assembly provided with a shaft and a plurality of beater plates mounted thereon for rotation in unison within said casing, each beater plate "having a number of'apertures disposed inwardly from its peripheral edge; a classifier section including a frusto-conical casing provided with. a discharge outlet at oneend and being substantially open at its other end for cooperation with the'open end of said cylindrical casing, and a rotor assembly provided with a shaft and a plurality of "classifying plates mounted. thereon for, rotation in unison, each classifying plate having anumber of apertures disposed inwardly from its peripheral edge; and means for separably connecting said casings together in axial alignment. i I i 2; The combination set forth in claim 1 in'which said plurality of classifying plates includes a primary classifying plate and a secondary classifying plate, said primary classifying plate being located within the axial confines of said cylindrical casing and the secondary classifying plate being located within the axial confines of said frusto-conical casing.

3. A combined pulverizer and classifier comprising; a pulverizer section including a casing provided with an inlet at one end for the introduction of material into the casing and being substantially open at its other end, and a rotor assembly provided with a shaft and a plurality of beater plates mounted thereon for rotation in unison within said casing, each beater plate having a number of apertures disposed inwardly from its peripheral edge; a classifier section including acasing provided with a discharge outlet at one end and being substantially open at its other end for cooperation with the open end of s'aid first casing, and a rotor assembly provided with a shaft which is rotatable independent of rotation of theshaft of the pulverizer section and a plurality of classifying plates mounted thereon for rotation in unison, each classifying plate having a number of apertures disposedinwardly from its peripheral edge; and means for'separably connecting said casings together in axial alignment.

4. The combination set forth in claim 3 in which said last-mentioned means includes a pair of hinge elements. 5 A combined pulverizer and classifier comprising: a pulverizersection including a casing provided with an plates within said casing in cantilever fashion; a classify-' shaft, a beater plate mounted near one end of said shaft having a number of apertures disposed inwardly from its peripheral'edge, and a pair of axially spaced bearings situated nearer the other end of said shaft for journaling said shaft for rotation of said beater plate within said casing in cantilever fashion; a classifying section provided with a discharge outlet at one end and being substantially open at its other end for cooperation with the open end of said first casing, and a rotor assembly provided with a second shaft and a plurality of classifying plates mounted thereon for rotation in unison, each classifying plate having a number of apertures disposed inwardly from its peripheral edge, and a pair of axially spaced bearings situated nearer the other end of said second shaft for journaling said second shaft for rotation of the plurality of classifying plates within said second casing in cantilever fashion; and means for separably connecting said casings together in axial alignment.

6. The combination set forth in claim 5 in which said last-mentioned means includes a pair of binge elements.

7. The combination set forth in claim 6 including driving means for said second shaft supported by said second casing so as to be movable with said second casing when it is swung into a separated position relative to said first casing.

8. The combination set forth in claim 5 including means for adjustably securing the classifying plate most closely adjacent the beaterplates in an adjusted axial position on said second shaft 9. A combined pulverizer and classifier comprising: a pulverizer section including a generally cylindrical casing provided with an inlet at one end for the introduction of material into the casing and being open at its other end,

its peripheral edge and said shaft, means limiting movement of the first of said plates away from said one shaft end, spacer means between said plates, means at said one end for retaining said plates on said shaft, and a pair of axially spaced bearings situated nearer. the other end of said shaft for journaling said shaft for rotation of said i-ng section including asecond casing provided with a discharge outlet atone end and being substantially open at its other end for cooperation with the open end of said first casing, a shaft, first and second classifying plates mounted near one end of said second shaft, 'said classifying plates each having a number of apertures spaced betweenits peripheral edge and said second shaft and said second classifying plate being equipped with a series of peripherally spaced 'whizzer blades, respective means i for anchoring each of said classifying plates at preferred axial locations on said second shaft so that said first classifying plate extends into said first casing and said second classifying plate resides within said second casing, and a pair of axially spaced-bearings situated nearer the other end of said second shaft for journaling said second shaft for rotation of said classifying plates in cantilever fashion; and means for separably connecting said casings together. 7 V

10. The combination set forthin claim 9 including tailings conduit meansleading from the open end of said first casing back to said inlet end, said means being free of internal protrusions .ortobs tructions V V p 11. The combination set forth in 'claimflld including a series of primary beater elements mounted radially inwardly from the peripheral edge of said first pulverizer plate on the rear side thereof, a second series of primary beater elements mounted on the side of the pulverizing plate opposite from the first-mentioned series, and a rear grind plate cooperable with said primary beater elements.

13. The combination set forth in claim 12 in which said casing connecting, means includes a pair of hinge elements.

14. A combined pulverizing and classifying unit comprising a first casing, said casing having an inlet and a substantially open outlet end, a shaft journaled for rotation in said casing, a beater plate mounted on said shaft, a second casing having an inlet end that cooperates with the outlet end of the first casing to receive material therefrom and a discharge opening, a shaft journaled for rotation in said second casing, a classifying plate mounted on the last-mentioned shaft such that said classifying plate extends into the outlet opening of the first casing, said classifying plate having apertures located in the central portion thereof, a conduit means free of internal obstructions and protrusions for recirculating classified coarse particles, said conduit means having a sole inlet opening in the first casing spaced radially outwardly from the classifying plate shaft and located adjacent to the outer peripheral edge of the classifying plate to recirculate the classified coarse particles before said particles enter the discharge area of the second casing, and means connecting the first casing to the second casing.

15. The structure of claim 14 further characterized in that there is provided means for adjustably retaining the classifying plate in an adjusted position along the axial length of the classifying plate shaft to adjustably vary the effective size of the conduit inlet opening.

16. A combined pulverizer and classifier comprising; a pulverizer section including a generally cylindrical casing provided with an inlet at one end for the introduction of material into the casing and being substantially open at its other end, and a rotary assembly provided with a shaft and a plurality of beater plates mounted thereon for rotation in unison within said casing, each beater plate having a number of apertures disposed inwardly from its peripheral edge; a classifier section including a frusto-conical casing provided with a discharge outlet at one end and being substantially open at its other end for cooperation with the open endof said cylindrical casing, and a rotary assembly provided with a shaft and a plurality of classifying plates mounted thereon for rotation in unison, each classifying plate having a number of apertures disposed inwardly from its peripheral edge; means for separably connecting said casings together in axial alignment, said plurality of classifying plates including a primary classifying plate and a secondary classifying plate, said primary classifying plate being located within the axial confines of said cylindrical casing and the secondary classifying plate being located in the axial confines of said frusto-com'cal casing, means for adjustably retaining the primary classifying plate in an adjusted position along the axial length of the classifying shaft, and means for adjustably retaining the secondary classifying plate in an adjusted position along the axial length of the classifying shaft.

17. A combined pulverizer and classifier comprising a pulverizer section including a generally cylindrical oasing having an inlet at one end for the introduction .of material into the casing and being substantially open at the other end, and a rotary assembly including a pulverizer shaft and a beater plate mounted on said pulverizer shaft for rotation in unison within said casing; a classifier section including a casing generally circular in cross-section having a discharge outlet at one end and being substantially open at the other end for cooperation with the open end of said cylindrical casing, and a rotary assembly having a classifier shaft that is independently rotatable of the rotation of the shaft of the pulverizer section, and at least one classifying plate mounted on the classifier shaft for rotation in unison with said classifier shaft, said classifying plate having at least one aperture disposed inwardly from its peripheral edge; and means for separably connecting said casings together in axial alignment, said heater plate and said classifying plate being secured in a position on their respective shafts to provide a structure free space therebetween bounded by a pair of spaced parallel planes perpendicular to the rotational axis of the shafts, the inner periphery of the casing, and the cylinder generated by rotating a line perpendicular tothe surface of the center portion of the classifying plate around said rotational axis.

18. The combination set forth in claim 17 in which there is provided means for adjustably securing the classifying plate in an adjusted position along the axial length of the classifying shaft.

References Cited in the tile of this patent UNITED STATES PATENTS 230,140 Lipsey July 20, 1880 745,075 Schutz Nov. 24, 1903 1,260,406 Lachmann Mar. 26, 1918 1,527,818 ONeill Feb. 24, 1925 1,621,571 Witz Mar. 22, 1927 1,765,309 O'Neill June 17, 1930 1,770,198 Chapple July 8, 1930 1,855,171 Holbeck Apr. 19, 1932 2,399,051 Maxson et a1. Apr. 23, 1946 2,573,129 Dulait Oct. 30, 1951 2,672,296 Venable Mar. 16, 1954 FOREIGN PATENTS 3,302 Great Britain of 1899 919,980 Germany Nov. 8, 1954 

